Antibiotics are not a proven treatment for asthma, yet the drugs are frequently prescribed to child asthma sufferers, according to a new study.

The results show 1 in 6 U.S. children (15.6 percent) who went to visit their primary care physician or the emergency department for asthma was prescribed antibiotics without justification. That equates to about 1 million children who received these drugs inappropriately.

This practice goes against U.S. and international guidelines that say antibiotics should be used in asthma patients only when they are also suffering from bacterial infections.

Such overprescription is problematic, the researchers say, because inappropriate use of antibiotics can fuel the spread of drug-resistant bacteria. Antibiotics also come with side effects that can spur additional problems, including severe diarrhea and yeast infections, said study researcher Ian Paul, a pediatrician at Penn State College of Medicine. The extra prescriptions and illness all boost medical costs, Paul said.

Asthma is a condition in which inflammation in the airways can lead to breathlessness, wheezing and coughing. Some studies suggest certain antibiotics can reduce inflammation in the airways. In addition, they can kill bacteria that commonly infect the respiratory tract. But the science simply is not there yet to recommend antibiotics as a treatment for asthma, Paul said, meaning no large study has found conclusive evidence of their ability to treat asthma.

Paul thinks the overprescription problem may be driven, in part, by physicians who use drugs as a crutch when a patient's asthma gets worse. The study found children were 2.7 times more likely to receive antibiotics if they were also prescribed corticosteroids, anti-inflammatory medication that is generally used when asthma symptoms become more severe.

The findings suggest that when children are sicker, "physicians are more likely to throw a whole bunch of medication at the child to try to treat them," Paul told MyHealthNewsDaily. "That’s probably not in the child's best interest."

In addition, doctors may prescribe antibiotics because they aren't sure if a child's respiratory symptoms are due to asthma or a respiratory illness such as pneumonia.

Paul said physicians should do as good a job as they can at distinguishing asthma symptoms from other disorders. They should also take the time to inform their patients about their decisions. The study found physicians who took extra time to explain the asthma treatment they were providing were 50 percent less likely to prescribe antibiotics, Paul said.

Patients should also make sure to ask their doctor why they are receiving a prescription for antibiotics, Paul said. This may help reduce needless use of the drugs.

The study was published online today (May 23) in the journal Pediatrics.